Effect of particle size on quality of crab meatballs using enzymatically deproteinized crab by-products

The production of crab meatballs generates large amount of crab shell waste, it is therefore necessary to develop a green, economical and environmentally friendly process to vaporize the waste. This study was aimed at investigating the applicability of microwave heating combined with ultrasonic field-assisted alkaline protease (MUSED) (50 ℃, pH = 9.0, 14025.67 U/g, 4.21 h and liquid/material = 14.41:1) for pretreatment of ball-milled crab shells. The ball milling efficiency of the crab shell powder pretreated by MUSED was observed to increase by 50 % compared to the control group, with the final average particle size of D₄ = 4.88 ± 0.20 um. High calcium solubility and low energy consumption of the ball-milled powder increased dietary calcium bioavailability and reduced the potential for high calorie intake. The addition of 6 % (w/w) crab shell powder treated by MUSED improved the texture of the crab meatballs (CM-D₄) and gave the product enhanced crab flavor relative to the control group. Moreover, the lower cooking loss of CM-D₄ resulted in significant retention of nutrients (p < 0.05). The crab shell powder treated by MUSED method was more efficient in ball milling, which improved the quality of crab meatballs while relieving environmental pressure.     

超滤与纳滤膜技术应用于桑叶中1-脱氧野尻霉素分离浓缩的效果观察

选桑叶为原料,以膜通量、膜通量衰减指数、DNJ透过率和杂质去除率为指标,探究三种超滤膜UF1、UF2和UF3对桑叶中1-脱氧野尻霉素（DNJ）分离效果以及两种纳滤膜NF1和NF2对DNJ的浓缩效果.研究结果表明：三种超滤膜中UF2最适于DNJ的分离,UF2-UF3联合处理（即UF3＊）的效果更佳,且两者的最优操作压力分别为0.8MPa和1.5MPa.与NF1相比,NF2蚋滤膜对DNJ的浓缩效果显著,浓缩倍数可以达到10.1,对DNJ的截留率为81.94％,DNJ纯度为4.65％.     

Quercetagetin loaded in soy protein isolate–κ-carrageenan complex: Fabrication mechanism and protective effect

In the present study, the potential of soy protein isolate (SPI)–κ-carrageenan (κ-CG) complex as a protective carrier for quercetagetin was investigated at different pH values (pH 2.3 and 6.5). The particle size of the ternary aggregates was slightly increased at pH 2.3, yet dramatically decreased at pH 6.5 with increasing quercetagetin concentration. Moreover, the negative ζ-potential of the ternary aggregates was increased significantly (p < 0.05) at pH 6.5. The addition of quercetagetin to the SPI–κ-CG complex could highly quench the intrinsic fluorescence of SPI. Circular dichroism spectra further suggested that the bound quercetagetin could induce the rise of β-sheet and β-turn contents at the cost of α-helix and unordered coil fractions of SPI. In addition, quercetagetin could increase the viscoelasticity of the ternary aggregates at both pH. Furthermore, the SPI–κ-CG complex was found to be superior to single SPI or κ-CG in terms of improving light stability and radical scavenging ability of quercetagetin.     

Mass spectrometry-based electric nose system for assessing rice quality during storage at different temperatures

A mass spectrometry-based electronic nose (MS e-nose) was used to measure changes in rice quality during storage at different storage conditions. Rice was stored for 4 months at four different temperatures (0 °C, 20 °C, 30 °C, and 40 °C) and tested for fat acidity, sensory characteristics, and flavor pattern analysis using the MS e-nose. When the rice was stored for long durations at higher temperatures, fat acidity increased and sensory quality was low. Flavor volatile profiles of the rice determined by MS e-nose revealed a tendency for the results to separate into three groups (months 1 + 2, 3, and 4). Volatile profile changes in rice during storage depended on the storage time, regardless of storage temperature. It is likely that the fat acidity and sensory evaluation results, which were related, could be distinguished by their volatile-producing metabolic activities. Accordingly, MS e-nose system was successfully used to screen and qualitatively evaluate stored rice.     

Variation in fatty acid composition of ewes' colostrum and mature milk fat

Temporal content variations of approximately 70 C4–C24 fatty acids (FA) in colostrum and milk of ewes consuming winter diet were determined by gas chromatography. The content of monounsaturated, polyunsaturated and straight-chain saturated FA 14:0–16:0 in colostrum was higher whereas the content of 4:0–12:0, 18:0 and branched-chain saturated FA 15:0–17:0 was lower than that in mature milk. The effect of ewe breed on the FA profiles was not significant. The composition of FA changed most significantly 1–2 days after lambing in agreement with the time schedule of colostrum formation. Nevertheless, the content of FA further successively changed up to approximately the 6th day of lactation, whereas further changes up to the 60th day of lactation were smaller. This is consistent with the recommendation that ewes' milk is suitable for human consumption after six-to-eight days of lactation. The higher contents of palmitic and myristic acids in colostrum compared with mature milk suggest that FA composition in colostrum matches the changing needs of the growing lambs.     

Low n-6/n-3 PUFA Ratio Improves Lipid Metabolism,Inflammation, Oxidative Stress and Endothelial Function in Rats Using Plant Oils as n-3 Fatty Acid Source

Lipid metabolism, inflammation, oxidative stress and endothelial function play important roles in the pathogenesis of cardiovascular disease (CVD), which may be affected by an imbalance in the n‐6/n‐3 polyunsaturated fatty acid (PUFA) ratio. This study aimed to investigate the effects of the n‐6/n‐3 PUFA ratio on these cardiovascular risk factors in rats fed a high‐fat diet using plant oils as the main n‐3 PUFA source. The 1:1 and 5:1 ratio groups had significantly decreased serum levels of total cholesterol, low‐density lipoprotein cholesterol, and proinflammatory cytokines compared with the 20:1 group (p < 0.05). Additionally, the 20:1 group had significantly increased serum levels of E‐Selectin, von Willebrand factor (vWF), and numerous markers of oxidative stress compared with the other groups (p < 0.05). The 1:1 group had a significantly decreased lipid peroxide level compared with the other groups (p < 0.05). Serum levels of malondialdehyde, reactive oxygen species and vWF tended to increase with n‐6/n‐3 PUFA ratios increasing from 5:1 to 20:1. We demonstrated that low n‐6/n‐3 PUFA ratio (1:1 and 5:1) had a beneficial effect on cardiovascular risk factors by enhancing favorable lipid profiles, having anti‐inflammatory and anti‐oxidative stress effects, and improving endothelial function. A high n‐6/n‐3 PUFA ratio (20:1) had adverse effects. Our results indicated that low n‐6/n‐3 PUFA ratios exerted beneficial cardiovascular effects, suggesting that plant oils could be used as a source of n‐3 fatty acids to prevent CVD. They also suggested that we should be aware of possible adverse effects from excessive n‐3 PUFA.     

Influence of ultrasonic treatment on the structure and emulsifying properties of peanut protein isolate

Effects of ultrasonic treatment on emulsifying properties and structure of peanut protein isolate (PPI) were evaluated by analysis of particle size distribution, protein surface hydrophobicity, SDS-PAGE, circular dichroism spectra and environmental scanning electron microscopy. The emulsifying properties of the PPI were found to be improved by ultrasonic treatment. The mean particle size decreased from 474.7 nm to 255.8 nm while the molecular weight remained unaffected. The results of intrinsic fluorescence spectroscopy and surface hydrophobicity indicated that ultrasonic treatment induced tertiary structural changes of the proteins in PPI. Emulsifying activity index and emulsion stability index were found to be correlated fairly well with surface hydrophobicity (H₀) (r = 0.712 and r = 0.668, respectively).     

芦笋下脚料中黄酮类物质分离纯化及鉴定

通过研究大孔吸附树脂的吸附和解吸性能,确定了AB-8型树脂分离纯化芦笋下脚料中黄酮类物质的条件为:吸附流速2mL/min,洗脱流速1.5mL/min;吸附原液pH6,洗脱剂为体积分数大于70%乙醇溶液,洗脱剂用量为200mL。纯化后的黄酮类物质经颜色反应和紫外光谱鉴定,主要为黄酮醇类。     

我国特殊医学用途配方食品产业现状与政策建议

特殊医学用途配方食品(特医食品)是指为满足特定患者和人群的营养需求,专门加工配制而成的食品,对疾病的预防和辅助治疗至关重要。我国特医食品产业起步以来,受到政府的日益重视。本文分析了我国特医食品产业现状,面临的机遇和挑战,提出相关建议,以期推动产业科技创新发展,助推食品产业供给侧结构性改革,提升国民营养健康水平。